A compound (amino-substituted azaspiroalkane) represented by formula (VIII):
(wherein, n stands for an integer of from 2 to 5) has been conventionally synthesized via a plurality of steps using ethyl acetoacetate as a starting material (JP-A-2-231475). An enantiomeric compound composed of a single isomer of the above-described compound has been so far prepared by converting a racemic modification of the compound into a diastereomer mixture having an optically active protecting group, separating a necessary isomer by preparative high performance liquid chromatography and then removing the protecting group (JP-A-3-95176). This process, however, needs a cumbersome operation and there was a room for improvement of it as an industrial process.
A preparation process utilizing the Strecker reaction or Dieckmann reaction was developed, but it is not industrially satisfactory, because a long reaction step is required for the conventional preparation process using such a reaction and in addition, asymmetric synthesis cannot be conducted readily.
An object of the present invention is to provide an industrially advantageous process for preparing, by convenient and short steps, an amino-substituted nitrogenous heterocyclic compound having a spirocyclic structure, particularly optically active amino-substituted [2.4]heptane derivative.